Heading out next Friday for the 2nd trip in my new 21SS (and the last one of the season ). I've been checking the 10-day forecast & the temps the 1st few nights are supposed to be in the 30s. Guess I'll be taking my down blanket & checking out the furnace in the Roo. The Roo has heated mattresses so I thought I might try those out also. EXCEPT I remembered that I have a 1-1/2" memory foam topper on the mattress. So, now I'm wondering if the mattress topper will block the heat from the mattress pad. Or if you should even try to use the heaters with a mattress pad? Especially memory foam since it's pretty dense. Anyone have any experience with this? Or and advice?

Heading out next Friday for the 2nd trip in my new 21SS (and the last one of the season ). I've been checking the 10-day forecast & the temps the 1st few nights are supposed to be in the 30s. Guess I'll be taking my down blanket & checking out the furnace in the Roo. The Roo has heated mattresses so I thought I might try those out also. EXCEPT I remembered that I have a 1-1/2" memory foam topper on the mattress. So, now I'm wondering if the mattress topper will block the heat from the mattress pad. Or if you should even try to use the heaters with a mattress pad? Especially memory foam since it's pretty dense. Anyone have any experience with this? Or and advice?

I have them too. I find they work best with a blanket on the bunk first.(this helps absorb any condensation you may get on bunk when its cold. Then the memory foam. Then a sheet over the mattress. Turn it on a few hours before bedtime and you will love it.

Last week we bought a 2" memory foam topper. We put it on and didn't use the mattress heater. Temps went down to about mid-40's. With flannel sheets, one blanket and a comforter, we were toasty. Not sure if the mattress heater would have "gotten through" the foam topper if we'd used it, but it certainly wouldn't have hurt.

Last year had just the mattress w/ heater and upper-30's and were fine.

In both cases, we had an electric heater turned on with the temperature setting down low, and the furnace set at 64 degrees as backup. It ran a few times.

If I were you, I'd hook up the mattress heater and if you need it, turn it on. I think you'll be OK.